'''UDP-glucose 4-epimerase''' (), also known as '''UDP-galactose 4-epimerase''' or '''GALE''', is a homodimeric epimerase found in bacterial, fungal, plant, and mammalian cells. This enzyme performs the final step in the Leloir pathway
metabolism, catalyzing the reversible conversion of UDP-galactose
GALE tightly binds nicotinamide adenine dinucleotide
(NAD+), a co-factor required for catalytic activity.
Additionally, human and some bacterial GALE isoforms reversibly catalyze the formation of UDP-''N''-acetylgalactosamine (UDP-GalNAc) from UDP-''N''-acetylglucosamine (UDP-GlcNAc
) in the presence of NAD+, an initial step in glycoprotein